Boosted LS management - someone please give me the Cliff's notes version

[Mr.Chevy4x4]

I'm not new to LS swaps, but I am new to turbocharging a Gen III engine. I have done a LOT of searching and reading, and I'm on information overload. Someone please school me on engine management.

Please don't limit your responses to answering just these questions, as they are only a few that just popped into my mind:

Best to eliminate the MAF and do a speed density tune?

What MAP sensor is best (mild boost < 12)?

Should I go with an aftermarket controller like microsquirt?

Being fairly engine and computer intelligent, should I buy software and try this myself or is a boosted application the wrong thing to be learning on?

My planned setup: Stock gen III 5.3 with 98 LS1 vette cam (it was free), LS6 springs, BTR push rods, trunion kit, 60# injectors, walbro 400, GT45 turbo, 50mm wastegate, air to air front mount intercooler, 4l80e, and 3.73:1 gears.

Initially planning 8-10 psi with 450-500 rwhp. May include meth injection at some point???

Thanks in advance,
Mike

[Overdriven]

I hear you on information overload. I've been spending a bunch of time on SloppyMechanics.com and their wiki page recently. Some good info there with "recipe" combos and even ecu tunes you can download/copy. If you're going to tune yourself, find one these downloadable tunes that best matches your combo and start from there. At least you'll be closer than starting from scratch with a stock tune. See if you can attend a tuning class though as there's more than just one fuel and one spark table you'lol be messing with in any ecu.

Which ecu? That depends a lot on your budget and what you want it to do. LS ecu is perfectly capable of running great with a turbo and they're arguably the best at controlling a GM auto trans. It's also more likely you'll find someone local to tune a stock LS ecu than an aftermarket one. If you already have a LS ecu there's not much reason to go aftermarket. But if you want to get fancy and have the ecu do other functions like boost control, antilag, nitrous control and such then an aftermarket ecu is a must as a LS ecu isn't capable of those things.

Map, go GM 3bar. Don't know how to convert to speed density, I assume that's something in the ecu done with software. You can do MAF with turbo but it can get complicated. If the MAF is before the turbo the blow off valve has to be recirculated since the air has already been metered by the MAF. Just dumping the air out the blow off without recirculating results in air fuel ratio going rich. MAF is harder to plumb than a MAP sensor. You're likely to peg most GM MAF sensors. The LS7 MAF is easier to plumb and can be put in larger tubes to keep it from being pegged but it will require more scaling in the ecu. Also there's street driving situations where a MAF tune can be fooled resulting in drivability issues.

Your engine combo. If you can swing it you'd be better served getting a mild turbo cam or LS9 cam than using the stock truck or 98 vette cam. Little John Stage 1 or 2 is pretty popular. If you haven't purchased injectors yet I'd go with 80lb instead of 60lb to lower duty cycle. Plus if you have the right stock injectors you can decap them for free and they'll flow about 60lb.

Gen3 internals are good for about 550whp max, your 450-500whp goal is a safer place to be. Plan on upgrading the pistons and rods before pushing for higher numbers. Gen4's have better rods and are the ones getting the high "stock bottom end" hp numbers. Pistons are basically the same between both generations and have pretty tight ring gaps. Opening up the ring gaps will help them live and is the one thing not stock about those "stock bottom end" engines claiming big numbers. Most failures can be traced back to a cylinder getting too hot closing the ring gap to nothing, binding the piston and causing it to break apart. With little to no piston on it the rod then flails around hitting the cam and oil pan before punching a hole in the block.

Meth is needed when your cylinder pressures or intake air temps are too high for the octane of fuel you're running. Spraying meth lowers intake air temps, adds octane and also adds some fuel. Got a pump gas combo that's limited to 10 psi before knock and want to push the boost higher? Spray some meth. Got a combo that starts to knock in the summer and don't want to back off the tune? Spray some meth. These are ways people use meth basically as a crutch but it can also be a safety net for combos that are normally safe as well. In my opinion you should always have your combo be safe when not on meth instead of tuned to the edge while on meth. Because if you're tuned to the edge on meth and you unexpectedly run out of meth or the meth injection fails your combo is no longer safe.

[BR3W CITY]

Originally Posted by Mr.Chevy4x4

I'm not new to LS swaps, but I am new to turbocharging a Gen III engine. I have done a LOT of searching and reading, and I'm on information overload. Someone please school me on engine management.

Please don't limit your responses to answering just these questions, as they are only a few that just popped into my mind:

Best to eliminate the MAF and do a speed density tune?

On lower boost it doesn't really matter. On higher boost levels you'll end up going SD because the MAF itself will become prohibitive.

What MAP sensor is best (mild boost < 12)?

A GM 2bar Map or TMap is all you really need. You could go up to 3bar, but if you never plan on building that level of boost, theres no reason to sacrifice the resolution (map tables are limited to a total # of cells on Gen III)

Should I go with an aftermarket controller like microsquirt?

No reason on this config. An HPT tune running the SD+CustomOS will let you run 1-2-3bar all day.

Being fairly engine and computer intelligent, should I buy software and try this myself or is a boosted application the wrong thing to be learning on?

Its like asking if a crotch rocket is the best first bike. Can you? Sure. Should you? Probably not.

My planned setup: Stock gen III 5.3 with 98 LS1 vette cam (it was free), LS6 springs, BTR push rods, trunion kit, 60# injectors, walbro 400, GT45 turbo, 50mm wastegate, air to air front mount intercooler, 4l80e, and 3.73:1 gears.

You may not even need 60# injectors.

Initially planning 8-10 psi with 450-500 rwhp. May include meth injection at some point???

Meth will depend on where your IAT levels end up, which will depend on the IC you run and what your charge and IAT temps end up being. I'm a fan of meth injection kits .

Thanks in advance,
Mike

bold and flavorful responses above.

[Mr.Chevy4x4]

Awesome! Thank you both for the valuable input. I'm still working out the details and buying parts. I think I've found someone in Raleigh that can handle the tuning. Has a good reputation with the LS folks.

I have made good progress on my manifold mods. I am going to shorten the right side and add a v-band flange so I can come off of it with a bend and get a little lower under the heater ports. I plan to run high mount a/c compressor so routing the hot side wasn't quite as easy as it could have been.

[BR3W CITY]

Looks like its coming together well.

[68basket]

excited to see this progress

[izzy_Britton]

curious to know why you went the low route on the exhaust manifolds rather than the high route? it seems very common to use the right manifold upside down on the left, and vise versa.

i ask purely out of curiosity as i will be starting a turbo build in the coming months.

thanks in advance.

-Izzy

[Mr.Chevy4x4]

I'm keeping my A/c and going with a high mount compressor setup, so that wasn't an option for me. The manifold would have been pointing directly at the compressor. It's making the task of building the hot side much more difficult, and I've thought several times about scrapping the A/C, but I really want to keep it as a driver/street bruiser.

Here is my compressor setup:

[BR3W CITY]

Will it clear the P/S pump and res?

[Mr.Chevy4x4]

Yes. I got the v-band flanges and reducers done today. I'll snap a pic tomorrow for you. I think there will be close to to 3/4 of an inch at the closest point.

Mike

[Mr.Chevy4x4]

Originally Posted by BR3W CITY

Will it clear the P/S pump and res?

Here's a pic of the clearance from the PS reservoir. It's at least 3/4 of an inch away. I think it will be fine as I plan to wrap the pipes. Still need to do the O2 bungs. And no, that nasty, crusty PS pump and bracket are not going on my truck. Just some I had available for mock up.

Mike

[Mr.Chevy4x4]

Here are a couple of pictures of the right side showing the clearance from the heater ports on the water pump. Not a huge gap, but far enough that I don't think it will cause any problems.

Mike